Effects of Different Types of Contraction Exercises on Shoulder Function and Muscle Strength in Patients with Adhesive Capsulitis

Although several studies have reported the effect of exercise therapy for adhesive capsulitis (AC), studies on the comparison of different exercise types on shoulder muscle strength and function in patients with AC are lacking. This study aimed to investigate the effect of different exercise types on shoulder muscle strength and function in patients with AC. Thirty female patients with AC were categorized into an eccentric contraction exercise group (ECG, n = 15; age, 51.53 ± 4.73 years) and a concentric contraction exercise group (CCG, n = 15; age, 52.40 ± 4.03 years). The participants in each group performed a different exercise program three times per week for 60 min per session for 12 weeks. The range of motion (ROM) of the shoulder joint, visual analog scale, shoulder muscle strength, and Constant–Murley score (CMS) were measured before the intervention and after 12 weeks of the exercise intervention. Shoulder ROM in flexion (increase of 31%) and external rotation (ER) (increase of 54%) showed a significant improvement in the ECG (p < 0.05). Muscle strength in ER was significantly different between the two groups (p < 0.05). Pain severity showed improvement in the ECG (decrease of 61%) after the intervention (p < 0.01). The CMS in the ECG (increase of 48%) showed a greater improvement than that in the CCG after the intervention (p < 0.01). This study showed that eccentric contraction exercise had a more beneficial effect than concentric contraction exercise for improving shoulder muscle strength and function in females with AC.

Effect of Eccentric and Concentric Contraction Mode on Myogenic Regulatory Factors Expression in Human Vastus Lateralis Muscle

Background: Skeletal muscle contractions are caused to release myokines by muscle fiber. This study investigated the myogenic regulatory factors, as MHC I, IIA, IIX, Myo-D, MRF4, Murf, Atrogin-1, Decorin, Myonection, and IL-15 mRNA expression in the response of eccentric vs. concentric contraction. Methods: Eighteen healthy men were randomly divided into two eccentric and concentric groups, each of 9 persons. Isokinetic contraction protocols included maximal single-leg eccentric or concentric knee extension tasks at 60°/s with the dominant leg. Contractions consisted of a maximum of 12 sets of 10 reps, and the rest time between each set was 30 seconds. The baseline biopsy was performed four weeks before the study, and post-test biopsies were taken immediately after exercise protocols from Vastus Lateralis muscle. The gene expression levels evaluated using Real-Time PCR methods. Results: A significant difference in MyoD, MRF4, Myonection, and Decorin mRNA, were observed following eccentric or concentric contractions (P≤0.05). The MHC I, MHC IIA, IL-15 mRNA has been changed significantly compared to the pre-exercise in the concentric group (P≤0.05). While only MHC IIX and Atrogin-1 mRNA changed significantly in the eccentric group (P≤0.05). Additionally, the results showed a significant difference in MyoD, MRF4, IL-15, and Decorin were observed at the follow-up values between eccentric or concentric groups (P≤0.05). Conclusion: Our findings highlight the growing importance of elucidating the different responses of muscle growth factors associated with a myogenic activity such as MHC IIA, Decorin, IL-15, Myonectin, Decorin, MuRF1, and MHC IIX mRNA in following to various types of exercise.

Eccentric Exercise Is Powerful but Can Be Painful

Your muscles can contract in different ways: when you walk upstairs, the muscles at the fronts of your thighs shorten (concentric contraction), whereas when you walk downstairs, they lengthen (eccentric contraction). Concentric contractions require more oxygen and thus make you burn more calories. Eccentric contractions are easier but break parts of the muscle and make you feel sore for several days. If you repeat eccentric exercises, however, your muscles will probably get bigger and stronger than they would by repeating concentric contractions. Most physical activities (like running and jumping) include both concentric and eccentric phases. Scientists have designed tools to study each type of muscle contraction, such as eccentric cycling, which uses a bike on which you must resist the pedals as they are driven backward by an engine.

Effect of Load, Angle, and Contraction Type on Clinically Assessed Knee Joint Position Sense

Context: Proprioception is an individual’s awareness of body position in 3-dimensional space. How proprioceptive acuity changes under varying conditions such as joint position, load, and concentric or eccentric contraction type is not well understood. In addition, a limitation of the variety of techniques to assess proprioception is the lack of clinically feasible methods to capture proprioceptive acuity. The purpose of this study was to implement a readily available instrument, a smartphone, in the clinical evaluation of knee active joint position sense and to determine how joint angle, joint loading, and quadriceps contraction type affect an individual’s active joint position sense. Design: Cross-over study. Methods: Twenty healthy, physically active university participants (10 women and 10 men: 21.4 [2.0] y; 1.73 [0.1] m; 70.9 [14.3] kg) were recruited. Individuals were included if they had no neurological disorder, no prior knee surgery, and no recent knee injury. The participants were given a verbal instruction to locate a target angle and then were tasked with reproducing the target angle without visual or verbal cues. An accelerometer application on a smartphone was used to assess the angle to the nearest tenth of a degree. Three variables, each with 2 levels, were analyzed in this study: load (weighted and unweighted), contraction type (eccentric and concentric), and joint position (20° and 70°). A repeated-measures analysis of variance was conducted to assess the within-subjects factors of load, contraction, and position. Results: A significant difference of 0.50° (0.19°) of greater error with eccentric versus concentric contraction (P = .02) type was identified. In addition, a significant interaction was found for contraction × position, with a mean increase in error of 0.98° (0.33°) at the 20° position when contracting eccentrically (P = .03). Conclusions: Contraction type, specifically eccentric contraction at 20°, showed significantly greater error than concentric contraction. This suggests that, during eccentric contractions of the quadriceps, there may be decreased proprioceptive sensitivity compared with concentric contractions.

Transfer of Muscle Strength Between Single-Joint and Multi-Joint Exercises for Lower Limbs

Most strength and conditioning coaches deal with the question in the training plan, how to supplement specific exercises, or which non-specific exercises would be the most suitable for achieving the set purpose. This study aims to assess what strength transfer with a focus on the lower limbs is projected from the selected strength intervention program (the right leg exercises only single-joint exercises: leg extension on machine and leg curl; the left leg exercises only multi-joint exercises: deadlift and leg press) to the force of the knee joint flexors and extensors during the eccentric and the concentric contraction. In one training session, the participants repeated every exercise five times in four series. The load intensity was around 90% of 1RM and was increased by 5% after the first and the fifth week. The rest interval was always three minutes long. For the left lower limb, the highest transfer (0.20) was from the leg press to the knee joint extensor at the eccentric contraction and from the deadlift was the highest transfer (0.19) to the knee joint extensor at the eccentric contraction. For the right lower limb, the highest transfer (0.53) was from the leg extension on a machine to the knee joint flexor at the concentric contraction and from the lying leg curl was the highest transfer (0.47) to the knee joint flexor at the concentric contraction.